基于高阶累积量的CPM信号调制阶数识别方法

Identification Method of Modulation Order for CPM Signal Based on Higher-order Cumulants

利用四阶累积量特征,提出一种CPM信号调制阶数的识别方法。提取过采样接收信号的相位,并进行差分;将相位差分结果向量化,得到若干子信道,每个子信道的输出都是平稳时间序列;利用四阶累积量特征可以区分不同概率分布的性质对调制阶数进行识别。该识别方法仅需已知码元周期,不需要关于调制指数,频偏、以及时延的信息,并且对脉冲成形波形长度过估计具有鲁棒性。仿真实验验证了理论分析结果,并给出了识别性能,以及在模型失配条件下的识别性能。

A new modulation order recognition method for continuous phase modulated（ CPM） signal is proposed based on forthorder cumulants. Firstly,the phase of the oversampled received signal is extracted and differenced. Secondly,the vectorization of the phase differences is performed to generate several sub-channels,and the output of each channel is a wide sense stationary time sequence. Finally,based on the property of higher order cumulant that can difference different probability distributions,the forth-order cumulant is chosen to recognize the modulation order of CPM signal. The proposed method only needs the knowledge on symbol period and is independent on modulation index,frequency-offset and time-offset. Moreover,it is robust to the over-estimation of pulse shape length. Through the simulation experiments,the theoretical analysis results are verified,and the recognition performance of proposed method with and without model mismatch are given respectively.